Field of the Invention
The present invention generally relates to wireless communication networks, such as cellular networks. More particularly, the present invention relates to cellular networks based on OFDM (Orthogonal Frequency Division Multiplexing) access schemes, such as LTE (Long Term Evolution)/LTE-A(dvanced) technology and their evolutions, and to a method for efficiently scheduling radio resources on such wireless networks.
Description of the Related Art
Evolution of cellular networks has experimented a significant growth in terms of spread and performance, and has recently brought to 3GPP (“Third Generation Partnership Project) LTE/LTE-A standard.
3GPP LTE/LTE-A standard is conceived for allowing data to be high-speed conveyed between a fixed-location transceiver base station or node (e.g., eNodeB—evolved NodeB) comprising antennas each radiating radio waves over a respective area—thus defining a so-called cell—and UE (User Equipments, e.g., user terminals, such as mobile phones) within such cell and in communication with said antennas.
A very important issue to be faced in multi-cell cellular networks is the inter-cell interference. Inter-cell interference mainly occurs when a UE is located at or near the border of two adjacent cells, so that the UE, despite being in communication (receiving/transmitting data) with one antenna of a base station, perceives radio signals radiated from one or more different antennas of the same base station or different base stations. In this situation, a mechanism of transmission/reception coordination between neighboring cells is required.
Several physical-layer and MAC-layer approaches are known in the art for facing the inter-cell interference issue.
For example, “Enhancing Cell-Edge Performance: A Downlink Dynamic Interference Avoidance Scheme with Inter-Cell Coordination” by Mahmudur Rahman, and Halim Yanikomeroglu, IEEE Transactions on Wireless Communications, vol. 9, no. 4, pp. 1414-1425, April 2010, discloses an interference management scheme comprised of two separate algorithms residing at the base station and at a central entity. Based on the interference received by its user terminals and their service status, each sector (via its base station) sends a request to the central controller; this request incorporates a tentative list of chunks to be restricted at the surrounding dominant interferer sectors. This request also includes the utility measure of the chunks in the requesting sector. The central controller gathers all such requests and processes to prepare a refined list of chunk restrictions to be applied in all involved sectors in different cells. The central controller sends the restriction decision to all involved sectors. The restriction process is refreshed from time to time within an interval which is shorter than the channel coherence time. Scheduler takes the restriction decision into consideration.